I can only compare the 2000S to the SVT because that is the only one I've tried. The SVT has more volume and the capability of better low end also, mainly because of it's active EQ circuit on channel 1. With suitable mods to the filter cap values in the first two stages (from 30uf to 110uf and 20uf to 50uf and replacing the GZ34 rectifiers with two Weber Copper Caps WZ34's) and upping the value of the cathode bypass cap on the first stage (go from 250uf to 300uf), the Sunn can give a much better bass response than stock and will still have more high end response than the SVT. The SVT still will have a better bass response again due to the active EQ. The Sunn sounds a little more responsive to picking attack also, and will distort more at higher volumes, which sometimes sounds cool.
The only way to really compare them accurately is to use the same cabinet for both sound tests because the SVT cabinet with the 8x10's will always have a more even and punchy response than the 2x15 Sunn cabinet. I like both sounds a lot and intend to use mine as Geddy Lee did, which the neck pickup of my Rickenbacker bass is sent to the SVT setup for clean, low end emphasised bass, and the bridge pickup is sent to an overdriven Sunn head. Mix the signals together for the best of both worlds.
